In the flame produced by the combination of hydrogen and oxygen, refractory metal melts like wax. But this flame is merely the production, from its elements, of water vapor— commonly called steam!—J. Milota.

Straight Tunnel Sags.

If a tunnel 40 miles long is perfectly straight, so that one might see through it, the center is 260 feet below the water level of either end; because of the curvature of the earth in that distance.